Have you thought about implementing foldable buttstock system? Like for AK family / Fal Folding buttstock / MP5. So when you fold it you reduce size by 1 verical square line, but in the same time it increases recoil (basically standard recoil can be used, the one that is without any stock). That will require 2-3 new animations ofc (but even one will be nice). This is not some critical bug or something, but having this would be nice, since you reduced the size of inventory, so this could fit perfectly.